1. Field of the Invention
The present invention relates to a method for manufacturing a silicon-on-insulator (SOI) substrate having a so-called SOI structure in which a semiconductor layer is provided on an insulating surface, and a method for manufacturing semiconductor device having an SOI structure.
2. Description of the Related Art
As an alternative to a silicon wafer which is manufactured by thinly slicing an ingot of a single-crystal semiconductor, an integrated circuit using a semiconductor substrate which is referred to as a silicon on an insulator (hereinafter also referred to as “SOI”) substrate in which a thin single-crystal semiconductor layer is provided on an insulating surface has been developed. The integrated circuit using an SOI substrate has attracted attention as an integrated circuit which reduces parasitic capacitance between a drain of a transistor and the substrate and improves the performance of a semiconductor integrated circuit.
As a method for manufacturing SOI substrates, a hydrogen ion implantation separation method is known (for example, see Patent Document 1: Japanese Published Patent Application No. 2000-124092). The hydrogen ion implantation separation method is a method in which hydrogen ions are implanted into a silicon wafer to form a microbubble layer at a predetermined depth from the surface to cause separation using the microbubble layer as a cleavage plane, and a thin silicon layer (SOI layer) is bonded to the other silicon wafer. In addition to the heat treatment for separation of an SOI layer, it is necessary to perform heat treatment in an oxidizing atmosphere to form an oxide film on the SOI layer, remove the oxide film, and perform heat treatment at 1000 to 1300° C. in a reducing atmosphere to increase bonding strength.
On the other hand, a semiconductor device in which a single-crystal silicon layer is provided over an insulating substrate such as a high heat-resistance glass substrate is disclosed (for example, see Patent Document 2: Japanese Published Patent Application No. H11-163363). As a structure of this semiconductor device, an entire surface of a crystallized glass substrate, a strain point of which is 750° C. or more, is protected by an insulating silicon film, and a single-crystal layer which is obtained by a separation method of hydrogen ion implantation is firmly fixed to the insulating silicon film.